PET (Puppy's Extra Treats) files are used in Puppy 2.14 and later. They are packages that add extra software. Pets are available from the Puppy Package Management system. Click on a downloaded Pet file to install software.

PET files should never be assumed interchangeable between versions. Sometimes it works - sometimes not.

An older pet is more likely to work on a newer puppy than the reverse.

When you compile a package, it looks at all the specifics of your OS and builds the program customized for that OS. Simpler programs need fewer specifics than complex ones - so simple stuff tends to be more portable.

Also, if your using a derivative its useful to find out which 'mainstream' version of Puppy its based on.

Pets are tarballs, just like '.tar.gz' files, with a MD5sum appended on the end. The in-built MD5sum is handy, as the file can be checked for integrity after being downloaded. They are used for packaging programs designed or compiled for Puppy and provide desktop icons, menu info etc specific to Puppy. Tarball files have a .tar extension. Or tar.gz if compressed with gzip. Pet files on the other hand have a .pet extension.